The G4S chief executive revealed the proposed acquisition on the morning of Monday, October 17. Buckles thought he had the backing of his leading shareholders after "positive" feedback from pre-marketing. Several institutions had even agreed to sub-underwrite the £2bn rights issue that would finance the deal, he was told.

However, when G4S shares slumped by 22pc it was clear all was not well. Advisers to the company claimed it was simply a technical repricing to reflect the deeply discounted rights issue. In reality, the City was in shock. "It became an uphill struggle from there," Buckles said on Tuesday.

For many investors, the security group had been a safe haven stock that had outperformed the market even during the recession. However, spending £5.2bn on a cleaning and catering group – with £2bn of new shareholder money and £3.7bn of debt – would create a radically different company.

Not only would G4S no longer be focused on security, but it would become one of the most highly leveraged companies in the FTSE 100. That was not the G4S that investors bought into.

During pre-marketing on the previous Thursday and Friday, Buckles tried to convince his 12 largest investors that G4S needed to do the deal because its customers increasingly wanted a wider range of services from its contractors.

However, these "briefings" lasted less than an hour and some were held over the phone. The shareholders say they were simply given a preview of an announcement that was ready to be made, and did not have enough time to digest the acquisition. Although many would need time to establish their opposition to the deal, they were already frustrated, surprised and uncomfortable at the way it had been presented.

One top 20 shareholder said: "It's like buying a flat for your girlfriend and then asking whether she likes it. Even though she will be paying for it."

Another said: "We are the owners of the business, not the investment banks. They trusted the investment bankers more than the shareholders and that is stupid."

The drop in the share price revealed the concerns but also spooked the institutions who had been willing to support it. Opposition became widespread. As well as the surprise strategic shift amid economic uncertainty, investors had doubts about the price being paid to the private equity owners of ISS and whether G4S could integrate a business that would have 1.2m employees around the world.

Privately and publicly, Kames Capital is the only leading shareholder to have confirmed it would have supported the deal. By the time G4S cancelled the shareholder vote on the deal on Tuesday, it was facing a landslide defeat.

"We clearly regret that we misread the market's appetite for deals of this scale," Buckles sad.

A top five City shareholder in G4S says Buckles should have approached it earlier about the deal and it would have agreed to not trade shares in the company. The investor would have urged Buckles to "revisit" the proposals before they were even made public, potentially saving G4S the embarrassment of the deal unravelling in front of the City. "It is not impossible that they could buy bits of ISS. Some bits of the business are very good. But the size and totality of it [the deal] was the problem," they added.

Buckles claims he was advised that approaching the shareholders just days before the announcement was "best practice". Meanwhile, the advisers to G4S – Deutsche Bank, Greenhill and RBS – are frustrated that institutions backtracked from their positive feedback during pre-marketing. A G4S source claims "several institutions" handed over letters saying they would sub-underwrite the rights issue. "There is something to learn for everyone from this," the source said.

Those lessons add to the ones garnered from the failed Prudential and AIA deal last year. G4S investors have again demonstrated that management and shareholders must engage properly, particularly if the investors are being asked to stump up fresh cash.

However, it is doubtful that Buckles could ever have persuaded shareholders against their view that the ISS deal was an unproven strategic shift that asked too much of them. His strong track record at G4S was no match for the scepticism of shareholders, which was exacerbated by volatile global stock markets. The one consolation for Buckles is that his prior track record is likely to ensure he keeps his job.